Center-finding instrument



E. T.' STRAUSS. CENTER FINDING INSTRUMENT.

APPLICATION FILED MAR 8, I920. 793 ]PatentedSept. 19 1922,]

9 2 SHEETS-SHEET I.

E.' T. STRAUSS. CENTER FlNDlNG INSTRUMENT. 7 I APPLICATION FILED MAR, B, 1920. 1,429,793, Patented Sept. 1-9, 1922'.

2 SHEETSSHEET -Z- Patented Sept. 1? 192,2.

EDWIN THEODORE STRAUSS,

attain earner center...

01? LA CROSSIE, WISCONSIN.

CENTER-FINDING INSTRUMENT.

Application filed March 8,

To (12K to from it may concern Be it known that I, EDWIN T; S'rRAUss, a citizen of'the United States, residing at La Crosse, in the county of La Crosse and State of isconsin, have invented certain new and useful Improvements in Center- Finding Instruments; and I do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to center-finding instruments, and more specifically to an improved machinists device for finding and indexing the exact center of a disk, cylinder, circular hole or other bodies having an arcuate surface.

One object of this invention is to generally improve upon devices of this character by providing a structure which is ex-- ceedingly convenient, accurate, durable, and compact, consistent with moderate cost of manufacturing, and which has a wide rangeof adjustments and uses, being provided with simple and efficient means to secure its work engaging abutments in their different adjustments.

Other objects and advantages are pointed out or implied in the following detailed description in connection with the accompanyin g drawings in which;

Fig. lis a top plan view of my improved center-finding instrument.

Fig. 2 is a rear end elevation.

Fig. 3 is a side elevation, a portion of the straight-edge being broken away.

Fig. 4. is a sectional view along the line ei of Fig. 1.

Fig. 5 is a sectional view along the line 5-5 of Fig. 1.

Fig. 6 is a sectional view along the line 6-6 of 1, the structure beyond the sec-- tion being omitted for the sake of clearness and the saving of space.

Referring to these drawings in detail in which similar reference characters correspond with similar parts throughout the several views, the invention comprises an indexing structure generally indicated at 1, a pair of work engaging abutments 2, and an adjusting device 3, the latter being operable to adjust the abutments 2 and hold them in their different adjustments with relation to a center-indexing edge 1, the latter being element of a straight-edge 1920. Serial No. 364 032.

which in turn forms an element of the indexmg structure 1. The straight-edge -5 has one of its longitudinal surfaces groovedfrom end to end as indicated at 6, the opposite surface or edge of this straight-edge,

being beveled from end to end as indicated at 7. The main body or positioning member 8 of the structure 1 is provided with a groove 9 which is undercut or has one of its walls extending inward, as indicated; at 10, over the bottom of the straight-edge 5 is fitted in the groove 9 and movable longitudinally, but held securely against lateral movement by the inclined or overhangingv surface 10 and a securing element which is preferably of the character shown in'detail in Fig. 6, comprising a screw threaded shank 11, a thumb-nut 12, and a head 13, the latter having a beveled surface 1 1 which engages with a beveled wall of the groove 6. It will be seen by referring to Fig. 6, that when the nut 12 is tightened against the body 8, the head 13 co-acts with the beveled surface l t for pressing the straight-edge against the bottom and the side 10 of the groove 9 and thereby effectually preventing lateral move ment of the straight-edge with relation to the positioning body 8. However, upon loosening the nut 12 very slightly, the straightedge is given freedom tomove longitudinally while being securely held against lateral movement in the groove 9.

The lower surface of the straight-edge is flush or level with the lower surface of the body 8, and this latter lower surface is substantially plane and constitutes a work-engaging surface, that is, the surface which is seated upon a disk, cylinder-end, or other arcuate piece of work whose radial center is to be found and indexed. The body 8 is formed with two indexing edges 15 and 16 which are in the same horizontal plane as the previously mentioned working surface and are, therefore, in the same horizontal plane with the indexing edge 4, it being understood that the indexing edges 1, 15 and 16 are the longitudinal corners between the vertical horizontal surfaces of the elements 5 and 8. It will be seen, therefore, that when this instrument is in working position on a plane surface, each of the indexing edges will be contiguous to the plane surface on which it is seated, and therefore, a scribers point, when passed along the indexing edges groove 9. The

edge 5 and terminates at a point substan tially in alinement with theindexing edge 4, this point being lndicated at 17 and constltutlng a center-lndexlng point which not only serves in finding or locating the axial center of the arcuate plece of work but also serves as a convenient meansof marking or indicating. the location of the center of a tube or other hollow cylindrical body, as

will be more clearly shown in a following partof the description. The body 8 is pro- 'vided with a notch or slot 18, having a wall 19 the end of which follows the line of the edge 16. From an inspection of Fig. 1 it will be seen that the line of the edge 16 extends at right angles to the line of the edge 15 and would intersect the same at the point 17. It, will be und'erstoodthat the center indexing point proper is that point at which .an-imagina-ry line which follows the line of the edge 16 will cross and intersect the, line of the edges o-fthestraightedge 5., The notch or slot 18 is suficiently wide to permit a scriber topass through and beyond the center-indexing point proper,

so that'when the device is used in finding the center of a relatively small tube-or hole, the material at diametrically opposite sides of the'tube or hole canbe scribed bypassing the scriber intoand along the notch or slot 18. The member 8 is beveled at 19 for thesake of convenience in seeing the indexing edge and passing the scriber therealong.

The indexing edge 16 terminates :at the slot 18, but is alinedwith thecenter-indexing point. Moreover, the indexing edges 15 and 16 are preferably arranged at right angles to one another and at angles of .t0 the scribing edge 4:, as shown, and although this is the preferable arrangement,

' the scribing edges 15 and 16 may be ar;

ranged at other angles than those specified, and one or both of these scribing edges 15 and 16 may be dispensed with when the straight-edge 5 is being used in connection with the adjustable work-engaging abutments 2 for finding centers under certain conditions, for instance, where the center is to be indicated by lines which cross one an other upon solid cylinders or disks, in which case, the abutments are placed against the periphery of the disk, as indicated in Fig.

I 1,- the circulardot and dash line representing the circumference of the disk.

The edge 1 of the straight-edge always crosses the exact center when the abutinents 2 are against the arcuate surface, and therefore,

bypassing the scriber along the indexing and then; turning thedevice about the point 17--so that the indexing edge crosses the mark which has pair of parallel guides or slots 21, and that the adjusting member 3 is provided with a pair of alined slots or guides 22, the latter crossing the. uides '20 and having flanged carriers 23 slidably seated therein, the flanges 24 and 25 of these carri rs extending into rabbets 25 and preventing accidentalremoval of the carriers from the slots 22. As shown in Fig. 4 the flanges 25 constitute edge extensions of plates which are secured to the main bodies of the carriers by means of screws 26. Each carrier 23 also comprises a roller 27, and a screw or .pintle 28 with. which the roller 27 is journaled, and these elements 27 and 28 extend into the slots 20, respectively, and are guided by the latter as the adjusting memher 3 is moved along the straight-edge 5. As the abutments 2 are carried by the respective carriers, and the latter are simultaneously and equally adjusted by their movement along the guides 20, it will be seen that the abutments 2 are always spaced 1 equally from the indexing-edge 4, in every adjusted position of these abutments toward and from the indexing-edge 4.

The adjusting member 3 is. preferably formed with parallel arms or wings 29 which are'apertured at 30 to receive screws or tightening members 31, the latter being provided with nuts 32 and held against ro tation of the squared portions which are embedded in the guiding heads 33 as shown in Fig. 5. These heads are provided with flanges 34, which-extend into rabbets 35 and prevent accidental disengagement of the members 33 from the guides or slots 21. Dowel pins 36 are seated in apertures of the members 29 and 33 so that these members can not turn about the screw 30, and the adjustingmember3 is thereby securely held at right angles to the indexing-edge 4: while being moved along the slots 21. However, the dowels or pins 36'are sufliciently short to permit the members 29 and 33 to exert a clamping action on the member 8, such clamping action being effected by means of the nuts 32, so that the adjusting member 3 may be securely held thereby in any adjusted position. Although two of the guides 21 and their respective sliding connectionsare illustrated and described, it is obvious that the device wouldbe operable if one of these guides and its adjunctswereomitted,

for the other guide 2 and its adjuncts would be sui'ficient under ordinary conditions, but the two guides are preferable because they provide additional strength and accuracy.

In operating the device for finding a center in space, that is, the axial center of a homer tube, the abutments 2 are seated against the inner or concaved surface, as indicated in Fig. 1, where the outer or dotted circular line represents the interior of the bore or tube or which the center is to be found, and when thus positioned, the index ting-edge 4. is always in registery with the axial center regardless of the size of the bore or the adjustment of the abutnients 2. How ever, the maximum accuracy is obtained when the abutn'ients 2- adjacent the outer ends of the guides $20 in connection with large bores, but it is essential, of course, that the abutments be adjacent the inner ends of the guides 20 in order that they may enter small bores. Having placed the instrument as described above, as shown in Fig. 1, a pencil or scriber is passed along the indexing edges 1 and 16 so as to marl: the material having the bore therein. The instrument is then turned so that the edge 4t registers with or is parallel to the mark which has been made along the edge 16. If the edge 4i re isters accurately w th this mark, the edge will register accui t ly with the mark which has been made along the edge 4, and this indicates or proves that the edges 15 and 16 point to the axial center of the bore and that the indexing point 17 is exactly at the axial center, this being true be cause the mark made along the edge 4; crosses the center, and whenthe edge 15 registers with this mark, it is noted that it also points to the center; and since the edges 4: and 15 are now both pointing to the center and meet one another at the point 17, this point is at the center of the bore. However, if the edge 4i does not register with the mark made along the edge 16, the edge 15 will not register with the mark made along the edge 4, but will be parallel to this mark, and may be brought into stry therewith by the abutments 2, or rather, adjusting the indexing structure w th relation to the bore by means of the abutments 2 so as to bring the parallel. edes and marks into registry and thereby ingthe indexing point 17 to the axial center.

The foregoing description of operation is given merely an example, and it is obvious this operation may be reversed by making the marks along the edges a and and then turning the device in the opposite directionf In laying out the center on a machine frame (for instance), where a boss or other obstruction might interfere in turning the instrument in one direction, it will be worked equally as well by reversing the operation or turning the device leftward instead of rightward, or rightward instead of leftward. Moreover, in order to avoid obstructions, the straight-edge 5' can be adjusted longitudinally as previously described; and for locating points or lines on diametrically opposite sides at given angles and at a distance from the center of the bore, this longitudinal adjustment of the straightedge 5 is very important.

Another manner of using this device for locating a point in space is shown in connection with the circles or broken circular lines 72 and c, in which 0 represents the outer circumference of a hollow cylinder or annulus, and .79 represents the bore or internal surface of this annulus. It will be seen that the surface between lines 0 and 5 extends past the open end of the slot 18, and that a scriber can be passed into the slot 18 for scribing entirely across this surface from the line b to the line 0.

Although I have described this embodiment of my invention very specifically it is not intended to limit this invention to these exact details of construction and arrange ment but changes maybe made within the scope of the inventive ideas as implied and claimed.

I claim:

1. In a center-finding instrument, an indexing structure provided with an indexing edge and two guides, said guides being arranged at equal angles to the said indexing edge and converging toward one another, a pair of worlcengaging abutments, and means engaged with and movable along said guides for simultaneously and equally adjusting said abutments toward and from said indexing edge.

2. In a center-finding instrument, an indexing structure provided with an indexing edge and two guides, said guides being arranged at equal angles to said indexing edge and converging towards one another, a pair of work engaging abutments, a pair of carriers by which said abutments are carried, and an adjusting member provided with a pair of guides which cross the converging guides of said structure, said carriers being engaged with and movable along the converging guides and one of the guides of said adjusting member.

In a center-finding instrument, an indexing structure provided with an indexing edge and a guide parallel with said indexing edge, a pair of workengaging abutments, disposed at oposite sides of said indexing edge, a pair of carriers adjustably connected to said indexing structure and movable to carry said abutments toward and from said indexing edge, and an adjusting member 'movably engaged with said guide and movable therealong and held against turning relative thereto, said adjusting member being connected with said carriers for causing themv to effect the ad j ustm ent of said abutments.

4t. lna center-finding instrument, an indexing structure provided with a substantially flat work-engaging surface and three indexing edges all in the same common plane, two of said indexing edges being on opposite sides of the third indexing edge and disposed at an angle to the latter and to one another, two abutments extending outward from said work-engaging surface and adapted to abut against an arcuate surface for causing said third indexing edge to register with a radius of the arcuate surface, and means for carrying said abutments adjustably mounted and movable to such positions with respect to said indexing edges that these abutments coact with we uate surfaces of ditl'erent radial extents for causing each oi? the two outer indexing edges to register with a radius of the respective arcuate surface whose center is being found.

5. In a center-finding instrument, an indexing structure provided with a substantially flat work-engaging surface and three indexing edges all in the same commonplane, two of said indexing edges being on opposite sides of the third indexing edge and disposed at an angle oi forty five degrees to the latter and ninety degrees to one another, two abutments extending outward from said work-engaging surface and adapted to abut against an arcuate surface for causing said third indexing edge to register with a radius of the arcuate surface, and means for carrying the said 'abutments adjustably mounted and movable to'such positions with respect to said indexing edges that these abutments coact with arcuate surfaces of different 'radial extents for causing each of the two outer indexing edges to register with a radius of the respective arcuate surface whose center is being found.

6. In a center-finding instrument, an indexing structure provided with two straight indexing edges which converge and meet one another to establish a center-indexing point, one oi said indexing edges extending through and in opposite directions beyond said indexing point, two work-engaging abutments carried by said indexing structure and being adjustable with relation to said indexing edges, and a third indexing edge at right angles to one of the first said indexing edges and alined with said indexing point but spaced from the latter a 'sulri cient. distance to permit a scriber tobe passed by the indexing center along the other one of the first said indexing edges.

'7. In a center-finding instrument, an indexing structure provided with a work-engaging surface and two indexing edges all arranged inv the same common plane, one of said indexing edges being at an angle to the second one and meeting the'latter at a center indexing point between the ends of said second indexing edge, 'andtwo workeng'aging abutments carried by said structure and being adjustable with relation to said indexing edges.

8. In a center-finding instrument, a structure provided with three straight indexing edges, two of said edges extending laterally from opposite sides of the other one and forming angles with the latter, said struc-' ture being provided withguides which extend laterally from opposite sides of the intermediate indexing edge and are disposed at equal acute angles to the latter, carriers mounted for movement along said guides, worlnengaging abutments carried by said carriers, an adjusting member engaged with both of said'carriers and operable to simultaneously and equally adjust said carriers along said guides, said adjusting member being eil'ective to secure said carriers in the1r ad usted posltlons. I 9. In a center-finding instrument, a structure] provided with three straight indexing edges, two of said edges extending laterally from opposite sides of the other one and forming angles with the latter,-said structure being provided with guides which extend laterally from opposite sides of the intermediate indexing edge and are disposed at equal acute angles to the latter, carriers mounted for movement along said guides, work-engaging abutments carried by said. carriers, an adjusting "member formed with guides which cross the first said guides and are engaged withsaid carriers in such relation that the latter are movable therealong, said structure beingprovided with'guides which are parallel to the intermediate indexing edge, said adjusting member being engaged with the last said guides and movable therealong.

10. The-device of the character described including a straight edge having a groove in one of its longitudnal edges, its opposite edge being beveled, a body formed wlth a recess 1n its under face, sald straight-edge being slidable through this recess, one of EDWIN THEODORE srnauss, 

